Downhole fiber-optic flowmeter: Design, operating principle, testing, and field installations

This paper discusses the design, operating principles, flow-loop testing, and initial field installations of the world's first all-fiberoptic flowmeter for downhole deployment. The flowmeter provides real-time measurement of the flow rate, phase fraction, pressure, and temperature. It is deployed with the production tubing and is rated to 125degreesC and 15,000 psi. It is fullbore, nonintrusive, electrically passive, has no moving parts, and overcomes the design limitations imposed by downhole environments. Thus, it has the potential to provide highly reliable downhole measurements The flowmeter has been tested extensively in industrial flow loops in a wide range of conditions. Results from the testing have demonstrated the flowmeter's ability to measure flow rates and water fractions in oil/water systems to within +/-5% for the entire range of water cuts. These results have been validated by data from several field deployments.